Hi there,
Just wanted to share with you how we managed to reduce the temperature from 21.5C to 19.5C, when I tried reducing it straight to 19.5C everyone felt cold so it was turned back up.
What I did was lower it by just 0.5C every two weeks or so, so know everyone is perfectly happy at 19.5C, it is far too hot if you come in after running, a bit cool if you just sit with a t-shirt however it is a comfortable temperature when you wear a long sleeved top.
I never feel cold even with a t-shirt though.
I am happy at 16.5C in my own room but no one else is, I get called a hot blooded teenager!